Hello,

I'm currently conducting investigation on how the surface area (or width) of a blade on a 3-bladed fan effect the power of the wind produced. I have done lots of research and it seems that there has been lots of experiments and calculations done on the effects of the number of blades and the effects of radius/diameter on power. However, there is little information on the effects of the surface area.

I was wondering whether someone can help me explain the relationship between the surface area of the blades and the power, whilst keeping the radius and number of blades fixed?

I have collected some data through an experiment where I had fans of the same radius but different surface area. I measured the velocity of the wind for each of the different fans.

To process my data, I decided to calculate the power, using the equation:

Power = 0.5*Area*Density of air*(velocity of wind)^3

I got this equation from my textbook regarding the calculation of maximum available power of wind energy (for turbines). And from research, I have found out that the Area is equal to swept area or the area of the full circle covered by the fan.

The question and problem I am facing is that if I use the area of the circle (swept area), my results will not have much difference as the area of the circle (swept area) is equal for each fan (and the velocities didn't have that much of a difference).

So if I want to show a difference in my result, is it better to use the total surface area of the blades instead of the area of the full circle? I mean, at any one point in time, the area of air that is getting pushed by the fan is where the blades are... - so wouldn't the total surface area of the blade prove to be a more accurate measure of the power produced by the fan?